Driver amplifiers are used in a wide variety of applications. In general, driver amplifiers are used to increase the power of signals. For example, driver amplifiers can be used to convert low-power radio frequency (RF) signals into larger RF signals for driving the antenna of a transmitter. In such cases, driver amplifiers may be implemented as part of overall power amplifier used by an RF transmission system.
Power amplifiers tend to consume a significant portion of the total power consumed by a transmission system. Therefore, the power amplifier's efficiency (i.e., the power of the amplifier output signal divided by the total power consumed by the amplifier) is an amplifier quality that designers consistently strive to increase.
However, amplifier performance also is important to consider, and many amplifier designs with high theoretical efficiencies may have characteristically lower performance. For example, some classes of amplifiers having relatively high theoretical efficiencies may have relatively poor performance in terms of linearity, distortion, bandwidth, and so on.
As there is a great desire to optimize both efficiency and performance in an RF power amplifier, designers of RF power amplifiers continue to strive to develop more efficient and higher performing amplifier designs.